Generally, an engine has such a characteristic that the output of the engine increases as the intake temperature of the engine decreases. Therefore, an opening portion for introducing outside air is provided in an engine cover in the case of an outboard motor in which the engine is covered with the engine cover.
However, when such an opening portion is simply provided at the engine cover, there is a fear that air sucked inside the engine cover through the opening portion may become high in temperature due to heat generated by the engine to thereby increase the intake temperature of the engine.
Therefore, in the background art, there is proposed an outboard motor provided with an intake device. The intake device is provided with left and right intake passages by which air introduced into the inside of the outboard motor through the opening portion of the engine cover is guided to a throttle body, and left and right interference type silencers which are provided in the middle of the intake passages respectively (e.g. see Patent Literatures 1 and 2).